Re: [PATCH] block: blk-rq-qos: guard rq-qos helpers by static key

[Jens Axboe <axboe@kernel.dk>]

On 4/17/25 5:08 AM, Yu Kuai wrote:
> 在 2025/04/15 22:52, Jens Axboe 写道:
>> Even if blk-rq-qos isn't used or configured, dipping into the queue to
>> fetch ->rq_qos is a noticeable slowdown and visible in profiles. Add an
>> unlikely static key around blk-rq-qos, to avoid fetching this cacheline
>> if blk-iolatency or blk-wbt isn't configured or used.
>>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> ---
>>
> LGTM
> 
> Reviewed-by: Yu Kuai <yukuai3@huawei.com>
> 
> BTW, do we want the same thing for q->td?

We may want to do that - I haven't seen that in the hot path yet,
but I also think I may have it configured out...

-- 
Jens Axboe